Helper Functions for Expressing Graphs

Note

To enable this feature, define the TBB_PREVIEW_FLOW_GRAPH_FEATURES macro to 1.

Helper functions are intended to make creation of the flow graphs less verbose.

Description

This feature adds make_edges, make_node_set, follows and precedes functions to oneapi::tbb::flow namespace. These functions simplify the process of building flow graphs by allowing to gather nodes into sets and connect them to other nodes in the graph.

API

Example

Consider the graph depicted below.

../_images/fg_api_graph_structure.png

In the examples below, C++17 Class Template Argument Deduction is used to avoid template parameter specification where possible.

Regular API

#include <oneapi/tbb/flow_graph.h>

int main() {
    using namespace oneapi::tbb::flow;

    graph g;

    broadcast_node<int> input(g);

    function_node doubler(g, unlimited, [](const int& v) { return 2 * v; });
    function_node squarer(g, unlimited, [](const int&) { return v * v; });
    function_node cuber(g, unlimited, [](const int& v) { return v * v * v; });

    join_node<std::tuple<int, int, int>> join(g);

    int sum = 0;
    function_node summer(g, serial, [&](const std::tuple<int, int, int>& v) {
        int sub_sum = std::get<0>(v) + std::get<1>(v) + std::get<2>(v);
        sum += sub_sum;
        returm sub_sum;
    });

    make_edge(input, doubler);
    make_edge(input, squarer);
    make_edge(input, cuber);
    make_edge(doubler, std::get<0>(join.input_ports()));
    make_edge(squarer, std::get<1>(join.input_ports()));
    make_edge(cuber, std::get<2>(join.input_ports()));
    make_edge(join, summer);

    for (int i = 1; i <= 10; ++i) {
        input.try_put(i);
    }
    g.wait_for_all();
}

Preview API

#define TBB_PREVIEW_FLOW_GRAPH_FEATURES 1
#include <oneapi/tbb/flow_graph.h>

int main() {
    using namespace oneapi::tbb::flow;

    graph g;

    function_node doubler(g, unlimited, [](const int& v) { return 2 * v; });
    function_node squarer(g, unlimited, [](const int&) { return v * v; });
    function_node cuber(g, unlimited, [](const int& v) { return v * v * v; });

    auto handlers = make_node_set(doubler, squarer, cuber);

    broadcast_node input(precedes(handlers));
    join_node join(follows(handlers));

    int sum = 0;
    function_node summer(follows(join), serial,
                         [&](const std::tuple<int, int, int>& v) {
                             int sub_sum = std::get<0>(v) + std::get<1>(v) + std::get<2>(v);
                             sum += sub_sum;
                             return sub_sum;
                         });

    for (int i = 1; i <= 10; ++i) {
        input.try_put(i);
    }
    g.wait_for_all();
}